Use FOIL to multiply two binomials.

FIRST: $\displaystyle{\left({2}{x}\right)}{\left({6}{x}\right)}={12}{{x}}^{{2}}\usepackage{cmbright}\Huge\$

OUTER: $\displaystyle{\left({2}{x}\right)}{\left(-{2}{y}\right)}=-{4}{x}{y}\usepackage{cmbright}\Huge\$ INNER: $\displaystyle{\left(-{3}{y}\right)}{\left({6}{x}\right)}=-{18}{x}{y}\usepackage{cmbright}\Huge\$

LAST: $\displaystyle{\left(-{3}{y}\right)}{\left(-{2}{y}\right)}={6}{{y}}^{{2}}\usepackage{cmbright}\Huge\$

Combine like terms: $\displaystyle{12}{{x}}^{{2}}-{4}{x}{y}-{18}{x}{y}+{6}{{y}}^{{2}}={12}{{x}}^{{2}}-{22}{x}{y}+{6}{{y}}^{{2}}\usepackage{cmbright}\Huge\$